Misalkan \((X,\tau_X)=(\{1,2,3,4\}, \{\emptyset,\{1\},\{2\},\{1,2\},X\})\) dan \((Y,\tau_Y)=(\{2,4,6,8\}, \{\emptyset,\{4\},\{6\},\{4,6\},Y\})\text{.}\) Definisikan \(f:X\to Y\) dengan \(f(x)=2x\text{.}\) Apakah \(f\) kontinu di \(4\text{?}\)